The present invention is directed toward a method and apparatus for strengthening the frame of a door, and, more specifically, toward a device mounted inside a hollow-core door to reinforce a portion of the door stile in the vicinity of openings that accommodate locking or latching hardware.
Doors have traditionally been formed from solid pieces of wood. As wood has become increasingly expensive, alternative types of doors have become more common. One such alternative door is formed by two parallel vertical stiles connected by top and bottom rails to form a rectangular frame and two thin panels or door skins attached to the frame to form a door with a hollow-core. Such doors are lighter than solid wood doors, have a lower material cost, and, if the space between the door skins is filled with a suitable insulating material, may provide better thermal insulation.
A first pair of aligned openings is provided in the door skins to receive a door handle or latching assembly and, optionally, a second pair of openings may be provided to accommodate a deadbolt or other lock. Latch bores extend through the stile next to these openings to allow a live bolt and/or a deadbolt to pass through the stile and into a corresponding opening in a doorjamb adjacent the latch side of the door. Optionally, a lock block with bores aligned with the door skin openings may be attached to the stile inside the door next to the latch bore to provide a secure mounting location for the door handle and lock hardware.
Drilling latch openings though a stile weakens the stile significantly, and it is known that doors may be forced by delivering a sharp kick or otherwise applying a force in the area of the latch bore to split the wooden stile. This weakening occurs even when a solid piece of a sturdy wood is used; with lighter woods, such as sometimes used in hollow-core doors to reduce weight, the problem is even more significant. When an ordinary door is kicked near the lock assembly, the metal strike plate in the doorjamb holds the distal end of the door bolt relatively securely while the door is forced slightly inwardly. As the door moves, the latch or bolt pivots within the bore, and if a great enough force is applied, snaps the stile near the latch bore. Once the end of the bolt inside the door begins to pivot, it can act as a lever to pry the strike plate out of the doorjamb when further force is applied to the door. If a first kick does not completely open the door, the latch will be damaged enough to allow some play and let the door move back and forth. Weakened in this manner, it is highly likely that a subsequent kick will completely break the bolt from the door and allow the door to be opened.
This problem has been recognized, and various attempts have been made to address it. For example, it is known from U.S. Pat. No. 5,586,796 to provide metal plates on the inside and outside faces of a door to reinforce the area around the lock and latch. While this approach does provide some additional strength, it also adversely affects the appearance of a door, giving it a commercial or industrial look. Alternately, U.S. Pat. No. 4,832,388 shows the use of unusually long screws for securing a strike plate to a doorjamb and for securing a reinforcing plate to the outer edge of the door, the screws being installed at an angle to the door and the doorjamb to make them more difficult to remove by force. However, this method requires that a large mortised region be formed on the outside edge of the door to accommodate the reinforcing plate. Moreover, because the reinforcing plate will be visible when the door is open, the plate should be made from a material with a finished appearance that matches the other door hardware, adding to the cost of the door. Furthermore, the oversized reinforcing plate may not be as aesthetically pleasing as the smaller plates that generally surround the live bolt of a door.
It would therefore be desirable to provide a reinforcement for a door that is economical to produce and install, that can be sold as an integral part of a hollow-core door, and that can be used without affecting the outward appearance of a door.
These problems and others are addressed by the present invention which includes a reinforcing plate mounted inside a door frame on the inner edge of the stile through which latch bores are drilled. In a preferred embodiment, the plate includes an opening aligned with each bore in the stile so that a live bolt or deadbolt can pass therethrough. When the door is closed and the bolt is extended, the bolt also extends though a strike plate mounted on a doorjamb and into an opening in the doorjamb. In one embodiment, the plate includes a flange surrounding each opening which flange extends into each bore to reinforce the bore and the stile. The flange preferably has at least one portion that is wider than the bore into which it is placed and may have outwardly flared or barbed end edges to help secure the plate to the stile. Alternately, or in addition, the plate may be dimpled or punched at locations spaced from the openings to form protrusions that extend into the stile to help secure the plate.
In a second embodiment, the plate is provided with several groups of screw holes arranged in circular regions lying on either side of each of the plate openings along the longitudinal centerline of the plate. When a latch plate is installed on the outer edge of the latch stile of a door incorporating the subject reinforcing plate, longer-than-usual screws are used to attach the latch plate to the stile, which screws extend thought the stile and pass through one of the screw holes in the plate and into the body of the lock block.
The plate in the door assembly of the preferred embodiment of the present invention provides support for a section of the bolt inside the door, away from the doorjamb. Thus, if a forced entry is attempted, the bolt is less likely to pivot in the door, and an intruder will essentially need to press the bolt, the reinforcing plate and the strike plate in a direction normal to the plane of the door to obtain entry. Because the reinforcing plate is securely mounted to the stile and the strike plate is secured to the doorjamb, a significant effort will be required to force the door open. While enough force will break any door, the present invention makes it appreciably more difficult to break down a door in the above-described manner.
Preferably, the subject plate is press-fitted to the inner edge of the stile while the door is being manufactured and thus does not require separate fasteners or adhesives to hold it in place. Furthermore, because the plate is inside the door, there is no need to provide a mortise to accommodate the plate and keep it flush with another surface. Also, because the plate is hidden after it is installed, it can be formed from an unfinished sheet of material, and the same material can be used on any door without regard for its outward appearance.
It is therefore a principal object of the present invention to provide a method of reinforcing a door that does not affect the outward appearance of the door.
It is another object of the present invention to provide an internally mounted reinforcing plate for a door stile.
It is another object of the present invention to provide a reinforcing plate that can be press-fitted to a frame of a door during manufacture.
It is yet another object of the present invention to provide a reinforcing plate having at least one flanged opening that is received in a latch bore in a door stile for reinforcing the stile.
It is yet a further object of the present invention to provide a method of reinforcing the frame of a door having more than one latch bore for accommodating more than one bolt.
In accordance with these objectives, a door is disclosed that includes a first stile having a front wall, a rear wall, an inner wall, and an outer wall; a second stile parallel to and spaced from the first stile and including an inner wall facing the first stile inner wall; a first door skin connected to the first stile and to the second stile; a second door skin connected to the first stile and to the second stile; a first lock bore extending through the first door skin and the second door skin; and a first latch bore extending from the first lock bore through the first stile inner wall and the first stile outer wall. The door also includes a reinforcing plate connected to the first stile inner wall having a first opening aligned with the first latch bore.
A method of forming a reinforced door is also disclosed, which method comprises the steps of: 1) taking a frame formed from first and second parallel side stiles having facing inner walls, a top rail connected between the first and second stiles and a bottom rail connected between the first and second stiles, 2) forming a latch bore having a diameter through the first stile, 3) taking a reinforcing plate including a flanged opening having a width greater than the first diameter and aligning it with the latch bore and pressing the flange into the latch bore until the plate contacts the stile and then attaching first and second door skins to the frame.
Another embodiment of a door according to the present invention includes a door frame having a latch stile, a hinge stile, and a top rail and a bottom rail connected between the latch stile and the hinge stile, the latch stile having an inner wall facing the hinge stile and a latch bore though the inner wall. A reinforcing shield has an opening with a flange with a first portion of the flange having a width greater than the width of the latch stile latch bore extends into the latch stile latch bore. A reinforcing shield overlies the latch stile inner wall and includes at least one projection extending into the latch stile at a location spaced from the latch stile latch bore. A lock block has a lock bore connected to the latch stile inner wall and has a lock block latch bore aligned with the latch stile latch bore. First and second door skins are connected to the door frame and having openings aligned with the lock bore.